Model airplane construction



Jan. 27, 1959 H. A. BERGSTRAND 2,870,

MODEL AIRPLANE CONSTRUCTION v I Filed July 29', 1957 2 Sheets-Sheet 1 H. A. BERGSTRAND ATTORNEY Jan. 27, 1959 H. A. BERGSTRAND ,5

MODEL AIRPLANE CONSTRUCTION Filed July 29, 1957 2 Sheets-Sheet 2 ATTORNEY Uni fi d Stat s 2,870,569 H I MODEL AIRPLANE CONSTRUCTION I 4 Harold A. Bergstrand, East Moliue, 111., assignor to Strombeck-Becker Mfg. Co., Moline, 111., a corporation of Illinois Application July 29, 1957, Serial No. 674,805 8 Claims. ((11. 46- 81) This invention relates to a toy or model airship and more particularly to a novel and improved construction incorporating such features as a fore-and-aft medial fuselage stiffener, transverse bulkhead means and improved fuselage-to-wing connections.

The invention relates especially to model airships of the type'assembled from basic light-weight shell-like components such as commonly produced by the process of vacuum-forming suitable plastic materials, and features significant improvements in reenforcement of normally structurally light or weak areas of the assembled ship by the provision of easily incorporated strengthening elements capable of being interiorly introduced during assembly and therefore largely concealed within the ship, particularly in the form of a stiffener and bulkhead means as aforesaid, the mounting of wing elements on projecting pads, and the internal strengthening of the pads by inserts fitted in and adhered to the internal surfaces of the fuselage about the recesses resulting from the formation of the pads. Still further objects reside in an improved nose section especially adapted for glider type models; the provision of a nose bumper; the adaptation of the bulkhead means as a pair of symmetrically positioned complementary box-like elements, one at each side of the stiffener and out of contact with the interior surfaces of the fuselage so as to strengthen the structure and yet to avoid undesirable stressing of the parts; improved launching means incorporated with the stilfener; and such other desirable features and important objects inherent in and encompassed by the invention as will appear from the disclosure of a preferred embodiment, byway of example, in the ensuing description and accompanying sheets of drawings, the several figures of which are described below.

Figure l is a perspective of a representative airshipof the glider type.

Figure 2 is a perspective of the stiffener and bulkhead assembly.

Figure 3 is an exploded perspective of the parts making up the assembly of Figure 2.

Figure 4 is an enlarged partial plan, partly in section, of the forward and intermediate portions of the ship.

Figure 5 is a section on the line 55 of Figure 4.

Figure 6 is a section on the line 66 of Figure 4.

Figure 7 is an enlarged section on the line 77 0 Figure l.

Figure 8 is a perspective, partly in section and drawn to an enlarged scale, of the nose section and bumper structure.

Figure 9 is a section on the line 9-9 of Figure 4.

Figure 10 is an exploded perspective of one fuselage half and its wing pad reenforcing structure as seen from the interior of the ship. I

Figure 11 is a similar view as seen from outside the ship.

In the following description the terms front and rear etc. will be used in their normal sense and right and left will be used with reference to the position ofa person behind the ship and looking forwardly.

ice

In general, and as seen in Figure l, the airship selected for purposes of illustration is representative of a scale model glider and has a fuselage 20, right and left wings or wing elements 22, a nose bumper assembly 24 and a tail assembly 26. The fuselage is made up of right and left fuselage halves or shells 28 complementarily assembled at opposite sides of a fore-and-aft medial plane and sandwiching therebetween at a fore part of the ship a fore-and-aft stiffener 30 which extends forwardly into the bumper assembly 24.

Each fuselage half is of shell-like or semitubular construction and is preferably a one-piece unit from front to rear. Since the manner of joining the symmetrical halves varies from front to rear, because of the stiffener 30, each half will be described as having a first or fore.

part 32 and a rear or second part 34. The distinction is made on the basis that the stiffener 30 is sandwiched between the fore parts 32, and the rear parts 34 extend rearwardly beyond the stiffener. The junction among the fore fuselage parts 32 and stiffener 30 and between the rear fuselage parts 34 is What may be considered a continuous junction lying generally in a common plane but since the stiffener 30 is plate-like, relatively rigid and of relatively thicker material than the fuselage halves, each fuselage half has its upper and lower marginal edge portions 36 and 38 laterally oifset in the forev part 32 relative to its upper and lower marginal edge portions 40 and 42 in the rear part. The upper and lower offsets clearly appearat 44 and 46 and afford pockets for receiving the rear part of the stiffener. The edges 36 and 38 are generally diametrically opposed or coplanar, and the same is true of the edges 40 and 42; considering the fuselage as symmetrical at opposite sides of an upright fore-and-aft plane including the stiffener 30. It should be observed that the stiffener could be horizontally disposed without sacrificing the benefits thereof, but it is preferred that the joint between the fuselage halves lie in an upright plane for reasons that are concerned with mounting of the wings 22. These edge portions are here in the form of integral flanges and the rear edges or flanges 40 and 42 are adhered respectively together and the fore part edges or flanges 36 and 38 are adhered respectively to opposite sides of the stiffener along upper and lower marginal edge portions 48 and 50 of the latter. in a typical assembly, conventional cement or adhesive is used but this is a detail not considered to constitute a limitation on the basic concept. or the exploitation thereof. Also, the parts are here drawn in somewhat exaggerated fashion as to thickness because of the difliculty involved in drawing these parts to accurate dimensions, it being a characteristic of vacuum-formed plastic material that it is extremely thin. This, in one respect, points up the significance of the reenforcing or strengthening elements to be elaborated below. At this point, it might be observed that the stiffener could extend the full length of the fuselage, but, since it is the fore part of the ship that bears the brunt of landing, collision and launching shocks, it is sufficient that the stiffener occupy only a forward zone. The oifsets at 44 and 46 admirably accommodate the stiffener and the arrangement retains the desired light weight and appearance. As will be seen, the stiffener and the fuselage halves have the same configuration intheir fore parts and are reduced in width as the nose of the ship tapers the launching aspect, the stiffener 30 has an integral de-j pending launching hook 52 exposed at the'bottom of the nose section; As is conventional, this book maybe 'us'e'd with any type of elastic medium, such as a rubber band, for launching the ship.

The forwardly tapered or reduced part of the stiffener that enters into the bumper assembly affords an integral forward stiffener extension and to each side of this is secured, as by adhesive, a reenforcing strip 55, here of the same material as the stiffener and preferably cut off the rear end of the stiffener as supplied in the kit from which the ship is assembled. These strips are cemented to the stiffener extension 54 before installation between the fuselage halves and these strips and the stiffener extension give the front part of the stiffener assembly a section of triple thickness. Each fuselage half has a comparable forward extension 58 shaped to form an interior pocket which overlies and accommodates the p: E nst-c strip 55 and this extension is flanged at so of. us continuaticns of the fuselage flanges 3'6 and 33 and further has an upright front flange 6d (Figure 8) all adhered to the respective side of the stiffener to conceal the strip and to retain the overall strcamlincu appearance of the ship. A bumper element 68, here a rubber cap having a tubular rear extension, is slipped over the bumper scction comprising the multiple thickness at 5 -56--$ and completes the bumper assembly.

The stiffener 3% not only comprises the backbone of the for part of the fuselage and embodies the bumper assembly 24, but also incorporates bulkhead means 78 in the Zone of the connection of the wings 22 to the fuselage. This bulkhead means comprises a pair of identical hollow or box-like elements 72, one secured to each of the opposite sides of the stiffener 36 adjacent to its rear part. Each element '17. is preferably formed of the same material as the fuselage halves and has a marginal flange '74 b means of which it is mounted on the stiffener by a typical cement or adhesive. The stiffener completes the box structure of each element by closing the open side thereof and the elements thus have a relatively high strength-tdweight ratio. The location of these elements is important not only because they are in the Zone of the wings-to-fuselage connections but also because, particularly in a glider model, the ship is normally gripped by the user at this point and the bulkhead elements prevent inad vertent collapse of the fuselage under gripping pressure. As best seen in Figure 6, the outer peripheral portion 76 of each bulkhead element is radially inwardly spaced from the interior surface of the proximate fuselage half 28 and is not secured thereto. Among the several reasons for this are the elimination of undesirable stresses in the fuseiage tiat might occur were adherence involved; improved cushioning of the fuselage when gripped, because the yield of the fuselage until stopped by the bulkhead elements is an indication to the user that sufficient gripping pressure is being exerted; and the avoidance of complications in assembly in the event that the elements are not accurately positioned on the stiffener 3 3. These elements have other advantages relative to the stiffener itself, particularly as to resisting twisting and lateral deflection. in order to reduce weight in the assembly, the stiffener is apertured as shown in the zone thereof intermediate the bumper assembly 24 and bulkhead means 7t).

The wings-to-fuselage connections involve novel and significant strudure, in regard to which attention is directed to Figures 4 and 91 1.

Each fuselage haif has, in a zone thereof involving bcth its fore and rear parts 32 and 34-, a laterally outwardly projecting, longitudi ally elongated wing mounting pad "78. Because of ti e nature of the formation of the fuselage half by the vacuum-forming method, the pad results in the formation of a conforming interior recess or pocket The same general structure would result of course from any equivalent molding or forming process and reference here to the vacuum-forming method is based primarily on the adaptability and relatively common use of that method in model planes and toys in general, particularly those furnished initially in kit form. Hence,

4 the method referred to does not establish a limit on the invention or the advantages and features thereof.

Each wing 22 is shown here as comprising upper and lower complementary halves 82 and 84 adhered or otherwise joined respectively to the upper and lower surfaces of the pads at 86 and 88 (Figure 9) and these wing halves may be peripherally flanged at 9%) and 92 respectively to afford a bonded juncture therebetween. in view of the shocks and strains imposed on the wings in flight, in collisions and in landing, it is desirable that the junctions thereof with the fuselage be improved, and to this end the invention affords novel strengthening members or inserts 94, one for each pad pocket 8i These are located of course within the fuselage and being concealed do not detract from the appearance of the ship.

Each insert or reenforcing member 94 is shaped as shown, being formed preferably of the same material as the fuselage halves and bulkhead elements and normally originally formed as part of the vacuum-formed cut-out sheet from which the ship is assembled. The projecting portion on each insert, as as 96, conforms to and closely fits in the respective pocket 89, and the portion 96 is bordered by a marginal flange 98 which abuts and is cemented at 10% to the fuselage portion about or bordering the pocket (Figure 9). The flange 98 itself adds strength but additional strength is afforded by an integral peripheral flange 102 which is normal to the flange 98. The projecting portion of the insert may be coated with cement before insertion in its pocket so that an added peripheral junction with the pocket is had at 104 (Figures 4 and 9).

if desired, the tail assembly could be based on the structure just described for the wing mounting. Likewise, additional bulkhead means like that at 70 could be provided elsewhere along the fuselage. However, the basic purposes of the invention ar found commercially to be more than adequate in the construction of a sturdy craft having desirable flight characteristics and the ability to withstand above average treatment without damage. All of the foregoing is accomplished by the novel reenfcrcing and bracing elements described, which as outlined, have the advantages of strength, light weight, low cost, concealment in whole or in part in the fuselage, etc.

Features of the invention other than those elaborated will readily occur to those versed in the art, as will modifications of the exemplary structure shown and described, all of which are obviously available within the spirit and scope of the invention.

What is claimed is:

l. in a toy airship: a fuselage comprising an elongated fore-and-aft nose stiffener of relatively rigid sheet material having opposite flat sides and opposite fore-and-aft marginal edge portions; a pair of complementary foreand-aft fuselage halves of relatively lightweight material and of semitubular section disposed respectively at opposite sides of the stiffener; each half having a front part alongside the proximate side of the stiffener and a rear part formed as a continuation of said front part and extending longitudinally beyond the stiffener; each front part having generally diametrically opposed flanged marginal edge portions coplanar with the associated side of the stiffener and secured to said side along the marginal edge portions of the stiffener so that the fore part of the airship about the stiffener is of triple thickness; and said rear parts having fore-and-aft marginal edge flanges formed respectively as continuations of said front part flanged edge portions and joined respectively together longitudinally beyond the stiffener in a fore-and-aft plane medially through the stiffener to afford a fore-and-aft double-thicknes rib medially of the rear part of the airship; each rear part edge flange being laterally inwardly ofliset immediately rearwardly of the stiffener to compensate for the inter ening thickness of the stiffener between the front part flanged edge portions 2. The invention defined in claim 1,

including: a

launching hook joined to the stifiener and projecting therefrom externally of the confines of the fuselage.

3. The invention defined in claim 1, including: transverse bulkhead means within the fuselage halves and projecting laterally beyond opposite sides of the stiffener, said bulkhead means comprising a pair of box-like elements, each having an open side facing toward the proximate side of the stiffener and a marginal flange bordering said open side and secured to said proximate side of the stiffener.

4. The invention defined in claim 3, in which: the sectional shape and transverse dimension of each bulkhead element is less than that of the associated fuselage half so that its periphery is spaced closely inwardly from the interior surface of said proximate fuselage half.

5. The invention defined in claim 1, in which: the stiffener and the front parts of the fuselage halves respectively have forwardly extended portions lying in side-by-side relation; the forwardly extended portion of each fuselage half is provided with a pocket facing the proximate side of the stiffener extension; and longitudinal reenfor-cing strips are secured respectively to opposite sides of the stifiener extension respectively in the pockets so as to triple the thickness of said stiffener extension.

6. The invention defined in claim 5, in which: the stiffener and fuselage extensions and the reenforcing strips are of reduced width as compared to the main width of the stiffener; and a resilient bumper is positioned ahead of the fuselage and has a tubular portion coaxially receiving said extensions and strips.

ginal edges adjoining to form an elongated hollow fuselage; a fore-and-aft stiffener of relatively more rigid sheet material than said halves and secured to said halves generally medially of the fuselage; and transverse box-like bulkhead elements projecting laterally outwardly from opposite sides of the stiffener within the fuselage, each element having an open side facing the proximate side of the stiffener and a marginal flange bordering said open side and secured to said proximate side of the stiffener.

8. The invention defined in claim 7, in which: each bulkhead element has a transverse dimension less than its associated fuselage half so that its outer periphery is closely spaced inwardly from the inner surface of said proximate fuselage half.

References Cited in the file of this patent UNITED STATES PATENTS 1,568,319 Cogswell Jan. 5, 1926 2,407,720 Mull Sept. 17, 1946 2,555,670 Babcock June. 5, 1951 2,560,742 Reder July 17, 1951 2,599,957 Walker June 10, 1952 2,770,072 Bast Nov. 13, 1956 FOREIGN PATENTS 37 Great Britain 1910 

